The present invention relates to tobacco cutting or shredding machines in general, and more particularly to improvements in tobacco cutting machines of the type wherein a continuous condensed cake of tobacco particles is advanced into the range of one or more orbiting knives at a severing or comminuting station so that the leader of the cake is converted into shreds or analogous fragments of tobacco. Still more particularly, the invention relates to improvements in apparatus for supplying particles of tobacco (e.g., tobacco leaf laminae or tobacco ribs) to the unit which converts the particles into a continuous cake.
It is well known to compress or compact particles of tobacco between the lower reach of an upper endless chain or belt conveyor and the upper reach of a lower endless chain or belt conveyor. The two reaches are inclined with reference to each other so that the height of the channel which is defined by such compacting conveyors decreases in a direction toward the comminuting station. The tobacco discharging end of the channel is adjacent to a mouthpiece through which the leader of the cake advances into the range of the orbiting knife or knives. The receiving or rear end of the channel is disposed above a rearwardly extending rear portion of the upper reach of the lower compacting conveyor and receives tobacco from the lower end portion of a duct the upper end portion of which receives non-compacted tobacco from a main source of supply, e.g., from a hopper for tobacco ribs or tobacco leaf laminae. As a rule, the channel is substantially horizontal and the duct defines a substantially vertical passage for advancement of the lower end of a pile of tobacco particles toward the receiving end of the channel. Reference may be had to commonly owned U.S. Pat. No. 4,037,712 granted July 12, 1977 to Wochnowski.
It is also known to provide the duct with a deflecting device which forms part of or is adjacent to the lower portion of the aforementioned passage and serves to promote the advancement of particles of tobacco toward the receiving end of the channel, i.e., onto the rear portion of the lower compacting conveyor. A deflecting device in the form of an oscillating rake is disclosed in commonly owned U.S. Pat. No. 4,149,547 granted Apr. 17, 1979 to Komossa et al.
The quality of shreds of otherwise configurated fragments which are formed at the comminuting station is satisfactory if the density of each and every portion or zone of the cake is constant. This enhances the comminuting acton of the orbiting knife or knives and reduces the likelihood that the knife or knives would extract entire laminae and/or ribs, i.e., that the knife or knives would fail to carry out a desirable and uniform comminuting action upon each and every particle in the cake. Uniform compacting of particles which form the cake can be accomplished by ensuring the delivery of tobacco particles at a constant rate, preferably by ensuring that the density of particles in the duct is constant and also that the height of the supply or pile of particles in the duct is at least nearly constant.
A critical zone of a tobacco shredding machine of the type wherein particles of tobacco descend in an upright duct toward and into a substantially horizontal compacting or condensing channel is that region where the direction of particles is changed from vertical or nearly vertical to horizontal or nearly horizontal. Any interruption of the mass of tobacco particles in such zone is likely to lead to the formation of an unsatisfactory cake which exhibits voids or wherein portions of greater density alternate with portions of lesser density. The change of direction of tobacco particles in the aforementioned critical zone is quite pronounced (normally approximately 90 degrees). In the absence of satisfactory feed of tobacco into the horizontal channel, the cake develops wedge-like voids which are not filled at all or which are filled only in part before the respective portion of the cake reaches the comminuting station. Unsatisfactory densification of the cake enables the orbiting knife or knives at the severing or comminuting station to extract entire tobacco leaf portions without any comminution or shredding. Absence of uniform density in all regions of the cake which is being shredded is the main cause of the formation of unsatisfactory shreds.